The European Union Aviation Safety Agency (EASA) has issued an Emergency Airworthiness Directive (AD) instructing airlines to implement a software fix on in-service Airbus A320 Family aircraft after a flight control vulnerability was discovered following an “uncommanded and limited pitch down event” involving an A320.
On 30 October, some JetBlue passengers were taken to hospital after a sudden altitude drop forced a diversion to Tampa International.
Analysis revealed that “intense solar radiation may corrupt data critical to the functioning of flight controls,” says Airbus, which issued an Alert Operators Transmission (AOT) before EASA’s AD dropped this evening.
With over 11,000 A320s in service in the world fleet and a “significant” number identified by the European airframer as likely to be affected, airlines are bracing for flight disruptions during a busy travel weekend especially as flyers return home after the US Thanksgiving holiday.
In its AD, which is effective at 23:59 UTC on 29 November, EASA explains: “An Airbus A320 aeroplane recently experienced an uncommanded and limited pitch down event. The autopilot remained engaged throughout the event, with a brief and limited loss of altitude, and the rest of the flight was uneventful.”
A preliminary technical assessment conducted by Airbus identified as a “possible contributing factor” a malfunction of the affected Elevator Aileron Computer (ELAC), which, as its name suggests, sends commands to both elevators and ailerons to control the aircraft’s pitch and roll. The affected ELAC is known as ELAC B L104.
“This condition, if not corrected, could lead in the worst-case scenario to an uncommanded elevator movement that may result in exceeding the aircraft’s structural capability,” EASA says.
EASA’s AD requires installation of a serviceable ELAC — the so-called ELAC B L103+ — on affected aircraft per Airbus’ AOT instructions, and otherwise prohibits installation of an affected ELAC on aircraft.
In some instances, “hardware protection” will first need to be employed to accommodate a fix, says Airbus.
For affected aircraft, says EASA, “before next flight after the effective date of this AD, replace or modify each affected ELAC with a serviceable ELAC in accordance with the instructions of the AOT. A ferry flight (up to three Flight Cycles, non-ETOPS, no passengers) is permitted to position the aeroplane to a location where the replacement or modification can be accomplished.”
Having worked proactively with EASA on the AOT in advance of the AD, Airbus says it “acknowledges these recommendations will lead to operational disruptions to passengers and customers. We apologise for the inconvenience caused and will work closely with operators, while keeping safety as our number one and overriding priority.”
The UK Civil Aviation Authority says “some” A320 Family aircraft registered in the UK “to some UK airlines” are affected. “The requirement will mean the airlines flying these aircraft will in some cases have to change software over the days ahead or remain on the ground from Sunday onwards until the software has been changed.”
Featured image credited to istock.com/Rathke
